The present invention relates to a composite nonwoven fabric having high dimensional stability and a process for preparing such nonwoven fabric.
Conventional fiber-entangled nonwoven fabrics prepared by a water jet treatment of a web composed of staple fibers, i.e., spunlaced fabrics, has been disadvantageous in that there is a significant difference between warp and weft tensile strengths and this drawback limits its application. To overcome this problem, there has already been a method proposed for improvement of such differential tensile strength, according to which, after a cross-stretching treatment, the resultant cross-stretched web is fixed by subjecting said web again to the water jets, or by use of a suitable binder or by a heat treatment causing fibers to be welded together, as disclosed, for example, in the Japanese Pat. Application Disclosure Gazette No. 49-42970.
However, use of a binder and fixation through fiber welding have been found to deteriorate the drape property and feeling of the fiber-entangled nonwoven fabrics obtained through the water jet treatment.
Fixation of nonwoven fabric through the fiber entanglement treatment by subjecting the web to the water jet treatment again after the cross-stretching, on the other hand, would certainly improve the cross direction/machine direction strength ratio of the nonwoven fabric through the fiber entanglement treatment only by the primary water jets, but the ratio of the initial tensile strengths in both directions contributing to the desired dimensional stability of the nonwoven fabric could not be adequately improved by this method. Such problem appears, for example, as a phenomenon that a machine direction tension easily causes a cross direction dimensional change(shrink) and a cross direction tension easily causes a machine direction dimensional change(shrink).
A principal object of the present invention is to provide, in view of the above-mentioned drawback of the prior art, a composite nonwoven fabric which is excellent in its drape property and dimentional stability.